CN220543151U - 40 micron small-diameter panda type polarization maintaining optical fiber - Google Patents
40 micron small-diameter panda type polarization maintaining optical fiber Download PDFInfo
- Publication number
- CN220543151U CN220543151U CN202322299417.XU CN202322299417U CN220543151U CN 220543151 U CN220543151 U CN 220543151U CN 202322299417 U CN202322299417 U CN 202322299417U CN 220543151 U CN220543151 U CN 220543151U
- Authority
- CN
- China
- Prior art keywords
- diameter
- coating layer
- stress
- fiber
- polarization maintaining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 230000010287 polarization Effects 0.000 title claims abstract description 29
- 208000025174 PANDAS Diseases 0.000 title claims abstract description 22
- 208000021155 Paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection Diseases 0.000 title claims abstract description 22
- 235000016496 Panda oleosa Nutrition 0.000 title claims abstract description 10
- 240000000220 Panda oleosa Species 0.000 title claims abstract 3
- 239000013307 optical fiber Substances 0.000 title description 45
- 239000000835 fiber Substances 0.000 claims abstract description 60
- 238000005253 cladding Methods 0.000 claims abstract description 28
- 239000011247 coating layer Substances 0.000 claims description 33
- 239000010410 layer Substances 0.000 claims description 27
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 5
- 239000004925 Acrylic resin Substances 0.000 claims description 3
- 229920000178 Acrylic resin Polymers 0.000 claims description 3
- 239000005388 borosilicate glass Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 description 20
- 230000008569 process Effects 0.000 description 16
- 238000004080 punching Methods 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 10
- 238000000576 coating method Methods 0.000 description 10
- 235000012239 silicon dioxide Nutrition 0.000 description 10
- 238000013461 design Methods 0.000 description 8
- 239000010453 quartz Substances 0.000 description 8
- 240000004718 Panda Species 0.000 description 7
- 230000008021 deposition Effects 0.000 description 6
- 238000000227 grinding Methods 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- YBMRDBCBODYGJE-UHFFFAOYSA-N germanium dioxide Chemical compound O=[Ge]=O YBMRDBCBODYGJE-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 238000005491 wire drawing Methods 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910003910 SiCl4 Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000010009 beating Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012681 fiber drawing Methods 0.000 description 1
- 229940119177 germanium dioxide Drugs 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- FDNAPBUWERUEDA-UHFFFAOYSA-N silicon tetrachloride Chemical compound Cl[Si](Cl)(Cl)Cl FDNAPBUWERUEDA-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Landscapes
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
Abstract
The application provides a 40 micron small-diameter panda type polarization maintaining fiber, which is characterized in that: the fiber core comprises a fiber core, a plurality of stress areas are arranged on the outer side of the fiber core, the stress areas are symmetrically distributed relative to the fiber core to realize stress area double refraction, a cladding layer is further arranged on the outer side of the cladding layer to cover the fiber core and the stress areas, the cladding layer is sequentially coated on the outer side of the cladding layer, the diameter of the cladding layer is 40+/-2 mu m, the diameter of the cladding layer is 80+/-5 mu m, the distance between the center point of the stress area and the fiber core is 9.5-11.5 mu m, the diameter of the stress area is 9-12 mu m, and the problem of miniaturization of the fiber-optic gyroscope is solved.
Description
Technical Field
The utility model relates to the field of fiber-optic gyroscopes, in particular to a 40-micrometer small-diameter panda-type polarization maintaining fiber.
Background
The fiber optic gyroscope is a navigation device which is currently used and developed in various countries because of the advantages of high precision, quick starting, large dynamic range, full solid state, impact resistance, strong interference resistance, long service life and the like. The high-precision development trend of the super-fiber gyroscope has very important significance for the development of national aerospace, national defense and industrial technologies.
The specifications of polarization maintaining optical fibers used by the fiber-optic gyroscope at present are 125/250, 80/165 and 80/135, and the market of the fiber-optic gyroscope is more and more high in precision and miniaturization in the development direction in continuously obtaining information fed back by clients, and the sizes of the existing polarization maintaining optical fiber products such as 80/165, 80/135 and 60/100 are greatly limited.
Disclosure of Invention
The utility model provides a 40-micron small-diameter panda-type polarization maintaining fiber, which solves the problem of miniaturization of a fiber optic gyroscope.
In order to solve the technical problems, the utility model adopts the following technical scheme: a40-micrometer small-diameter panda type polarization maintaining fiber is characterized in that: the fiber comprises a fiber core, wherein a plurality of stress areas are arranged on the outer side of the fiber core, the stress areas are symmetrically distributed relative to the fiber core to realize stress area type double refraction, a cladding layer for cladding the fiber core and the stress areas is further arranged on the outer side of the cladding layer, the cladding layer is sequentially coated with a coating layer, the diameter of the cladding layer is 40+/-2 mu m, the diameter of the coating layer is 80+/-5 mu m, the distance between the center point of the stress area and the fiber core is 9.5-11.5 mu m, and the diameter of the stress area is 9-12 mu m.
In a preferred embodiment, the coating layer comprises an inner coating layer coated on the outer side of the cladding layer and an outer coating layer coated on the outer side of the inner coating layer, wherein the inner coating layer and the outer coating layer are double-layer acrylic resin materials cured by ultraviolet light, the elastic modulus of the inner coating layer is 0.05-10 mpa, and the elastic modulus of the outer coating layer is 500-3000 mpa.
In a preferred embodiment, the stress region has a circular structure made of borosilicate glass, and the doping concentration of the stress region is such that the refractive index difference of the stress region relative to the quartz glass is-0.012 to-0.018.
In a preferred embodiment, the operating wavelength is 1310nm and 1550nm.
The beneficial effects of the utility model are as follows: under the condition of the same length of optical fiber, the Sagnac coil of the fiber optic gyroscope wound by the small-diameter polarization maintaining optical fiber can greatly reduce the volume weight of the ring, and is beneficial to manufacturing the miniaturized fiber optic gyroscope; the bending resistance of the optical fiber is increased due to the reduction of the outer diameter of the optical fiber, and the winding diameter of the optical fiber ring can be reduced, so that the volume of the optical fiber ring is reduced, and the miniaturized optical fiber gyroscope is also facilitated to be manufactured; under the condition of the same ring, a fiber gyroscope with the same precision is wound, longer fibers can be wound on the same layer by using the small-diameter polarization maintaining fibers, the number of wound layers is reduced, so that the stress effect between the fibers caused by layer-by-layer superposition is reduced, meanwhile, the thickness of the fibers in the fiber ring is reduced due to the reduction of the number of layers and the thinning of the fibers, and when the environmental temperature condition is changed, the difference between the temperature of the inner layer and the temperature of the outer layer of the fibers is reduced, thereby being beneficial to improving the environmental adaptability of the fiber gyroscope and improving the temperature characteristic of the fiber gyroscope; the length of the optical fiber preform rod with the same size which is drawn into the small-diameter polarization-maintaining optical fiber is more than several times of the length of the common polarization-maintaining optical fiber, and the cost of the corresponding polarization-maintaining optical fiber is also greatly reduced.
Drawings
The utility model is further described below with reference to the drawings and examples.
Fig. 1 is a schematic cross-sectional view of an optical fiber of the present utility model.
Fig. 2 is a schematic view of an optical fiber preform according to the present utility model.
Fig. 3 is a process sequence diagram of the drawing device of the present utility model.
In the figure: a core 1; a stress region 2; a cladding layer 3; an inner coating layer 4; an outer coating 5; a punching bar 6; a stress bar 7; an extension rod 8; an extension tube 9; a special plug 10; an air duct 11; a sealing device 12; a feeding device 13; a preform 14; a wire drawing furnace 15; a first applicator 16; a first curing station 17; a second applicator 18; a second curing station 19; a tension sensor 20; and a fiber collecting system 21.
Detailed Description
As shown in fig. 1-3, a 40 μm small diameter panda type polarization maintaining fiber is characterized in that: the fiber comprises a fiber core 1, wherein a plurality of stress areas 2 are arranged on the outer side of the fiber core, the stress areas 2 are symmetrically distributed relative to the fiber core 1 to realize stress area double refraction, a cladding layer 3 for cladding the fiber core 1 and the stress areas 2 is further arranged on the outer side of the cladding layer 3, a coating layer is sequentially coated on the outer side of the cladding layer 3, the diameter L1 of the cladding layer 3 is 40+/-2 mu m, the diameter of the coating layer L3 is 80+/-5 mu m, the distance from the center point of the stress areas 2 to the fiber core is 9.5-11.5 mu m, and the diameter of the stress areas is 9-12 mu m.
In a preferred embodiment, the coating layer comprises an inner coating layer 4 coated on the outer side of the cladding layer and an outer coating layer 5 coated on the outer side of the inner coating layer 4, wherein the inner coating layer 4 and the outer coating layer 5 are double-layer acrylic resin materials cured by ultraviolet light, the elastic modulus of the inner coating layer 4 is 0.05 to 10mpa, the diameter L2 is about 60 mu m, and the elastic modulus of the outer coating layer 5 is 500 to 3000mpa.
In a preferred embodiment, the stress region 2 has a circular structure made of borosilicate glass, and the doping concentration of the stress region 2 is such that the refractive index difference of the stress region relative to the quartz glass is-0.012 to-0.018.
In a preferred embodiment, the operating wavelength is 1310nm and 1550nm.
The 40-micron thin panda-type polarization maintaining fiber has the cross section of only 37% of an 80/135 fiber, and the ring volume of the low-precision fiber-optic gyroscope can be reduced by more than 50%, so that the size of the fiber-optic gyroscope can be further reduced, and the small-sized fiber-optic gyroscope meets the application requirement of miniaturization of the current low-precision fiber-optic gyroscope. When the high-precision fiber optic gyroscope is applied, the winding length of the annular ring with the same volume can be increased by more than 50%, and the precision of the fiber optic gyroscope is further improved under the condition that other dimensional designs are unchanged.
The mode field matching design is adopted, so that the 40-micrometer thin panda-shaped optical fiber can be welded with other devices on the gyroscope, such as a Y waveguide, and the engineering application of the 40-micrometer thin panda-shaped polarization-maintaining optical fiber is promoted. Secondly, in order to solve the balance of crosstalk performance and loss requirement, the optical fiber design is optimized in the project, the traditional bending insensitive optical fiber technology is transplanted into the small-diameter polarization-preserving design, and the cladding is adopted to sink, so that the influence of boron diffusion in a stress area on attenuation can be prevented, the material dispersion of an optical fiber core can be restrained, meanwhile, the doping concentration of germanium dioxide in the optical fiber core can be reduced, the purpose of reducing the Rayleigh scattering loss of the optical fiber and further reducing the optical fiber loss is achieved, and on the basis, the distance between the stress area and the optical fiber core can be further retracted to improve the crosstalk level.
The development process relates to the whole process of panda polarization maintaining fiber manufacture, and the main technical approach is as follows: and manufacturing high-quality single-mold core rods and stress rods by adopting FCVD and MCVD processes. The main process comprises the following steps: the main process recipe is determined based on parameters (e.g., inner cladding diameter, core-cladding refractive index difference, etc.) of the pre-designed single core rod and stress rod. And selecting a high-quality quartz tube as a reaction tube, adopting FCVD and MCVD processes, and manufacturing the prefabricated rod through the determined technological parameters such as the proportion relation of raw materials, the deposited layer number and the like. The method mainly comprises the following steps:
step one: preparation of single-mode preform
The FCVD technology is adopted, raw materials such as SiCl4, geCl4 and the like are carried by high-purity O2 and pass through a quartz tube, meanwhile, a oxyhydrogen flame is used for heating the quartz reaction tube, the raw materials and the high-purity O2 are subjected to chemical reaction at high temperature in the quartz tube, the SiO2 and the GeO2 generated after the high-temperature reaction are uniformly deposited on the inner wall of the quartz tube along with the rotation of the quartz tube and the movement of a heating lamp cap, and the required deposition thickness is controlled by controlling the deposited layer number and the flow of the raw materials. The doping amount in the high-purity SiO2 material, deposition temperature, deposition speed, deposition layer number and other parameters are used for controlling the size and refractive index distribution of the preform, so that the single-core rod meeting the optical parameters of the final polarization maintaining optical fiber is obtained
Step two: core rod melt shrinkage
The outer diameter of the single-mode core rod prepared by the FCVD process is about 18 mm-24 mm, the single-mode core rod cannot be directly prepared into a polarization maintaining optical fiber preform, and the polarization maintaining optical fiber preform needs to be sleeved to a diameter range meeting the process design requirement, so that the single-mode core rod needs to be sleeved. After the core rod is cleaned, the core rod needs to be centered and adjusted with the quartz tube, so that the eccentricity of the prefabricated rod caused by a sleeve process is prevented. And then fixing the mother rod and the quartz tube together by a lamper through an oxyhydrogen flame heating method, forming a closed system after the adjustment welding of a high-precision sleeve lathe, and completing sleeve welding through an oxyhydrogen flame and vacuumizing combination method.
Step three: preparation of highly doped stress rod
Preparing a high doping stress rod by adopting MCVD or FCVD, wherein the doping concentration reaches more than 25 percent, which is 20-23 percent higher than that of a common 80 mu m polarization-maintaining optical fiber, the size of a doped core region is 10-16 mm, and the roundness is less than 1 percent; the key technological parameters for preparing the stress rod with the outer diameter of 16-25 mm comprise the flow rate of raw material gas, the pressure of a deposition area, the deposition temperature and the moving speed of a lamp cap.
Step four: stress rod polishing
And processing the stress rod by adopting a special multifunctional grinding machine. The surface of the stress rod is ground by controlling the longitudinal feeding amount of the grinding machine and the rotation speed of the grinding wheel, the stress rod is polished by replacing the polishing grinding wheel with a higher modulus after the grinding is finished, and the final polishing outer diameter is 16+/-1 mm.
Step five: punching holes
And (3) punching the melt shrinkage rod by adopting a deep hole drilling machine, and ensuring the axial flatness of the fiber core of the single-mode preform rod if the centers of the two holes and the center of the fiber core are on the same straight line. Develop the full clamping device of preformed rod, guarantee the stability of the in-process stick of punching, we have carried out design optimization to the tool bit of punching simultaneously, make it possess the function of taking the polishing of beating in succession, under the prerequisite of guaranteeing parallelism and degree of depth of punching, improve the inner wall quality of the stick of punching, simultaneously, utilize the optical fiber endoscope to detect the roughness of punching, ensure the quality of the stick of punching.
Step six: polarization-preserving preform assembly
A panda type polarization-maintaining optical fiber preform is manufactured by adopting a punching and embedding process and comprises a punching rod 6, a stress rod 7, an extension rod 8, an extension tube 9 and a special plug 10. After the single-mode preform and the stress preform are fabricated, they are combined together as required by the design.
Step seven: wire drawing
The drawing device is shown in the figure according to the process sequence, and comprises an air duct 11, a sealing device 12, a feeding device 13, a prefabricated rod 14, a drawing furnace 15, a first coating device 16, a first curing station 17, a second coating device 18, a second curing station 19, a tension sensor 20 and a fiber collecting system 21.
Compared with the traditional 80 mu m optical fiber drawing process, the 40 mu m thin panda type polarization maintaining optical fiber has the advantages that the cladding and the coating are thinned integrally, the central hole of the optical fiber coating die is correspondingly reduced, and the aperture of the 40 mu m thin panda type polarization maintaining optical fiber coating die is smaller. So the drawing process parameters of the 40-micrometer thin panda-type polarization maintaining optical fiber are different from those of the 80-micrometer drawing process.
Firstly, under the condition of the same drawing speed and temperature, the drawing tension of the 40-micrometer small-diameter panda-type polarization maintaining optical fiber is small, the feeding speed is low, and the drawing is performed for a long time in a drawing furnace, so that the problems of strength and coating quality are at certain risk. So that the drawing temperature of the 40-micron thin panda-type polarization maintaining fiber is lower than that of the 80-micron polarization maintaining fiber if the drawing conditions are the same as those of the 80-micron polarization maintaining fiber; and the drawing speed and the drawing temperature are related to each other, and the drawing speed of the 40-micrometer thin-diameter panda-type polarization maintaining optical fiber needs to be improved relative to that of the 80-micrometer polarization maintaining optical fiber under the same drawing temperature in order to ensure proper tension. Finally, the curing degree is lower than that of the 80 mu m optical fiber coating, so that the optical fiber coating is easier to cure. Therefore, by adopting a coating die with smaller size, the drawing temperature is reduced, the drawing speed is increased, and the optical fiber meeting the design requirement is prepared.
Through the process, the prepared optical fiber can meet the following optical fiber indexes.
The above embodiments are only preferred embodiments of the present utility model, and should not be construed as limiting the present utility model, and the scope of the present utility model should be defined by the claims, including the equivalents of the technical features in the claims. I.e., equivalent replacement modifications within the scope of this utility model are also within the scope of the utility model.
Claims (4)
1. A40-micrometer small-diameter panda type polarization maintaining fiber is characterized in that: the fiber comprises a fiber core, wherein a plurality of stress areas are arranged on the outer side of the fiber core, the stress areas are symmetrically distributed relative to the fiber core to realize stress area type double refraction, a cladding layer for cladding the fiber core and the stress areas is further arranged on the outer side of the cladding layer, the cladding layer is sequentially coated with a coating layer, the diameter of the cladding layer is 40+/-2 mu m, the diameter of the coating layer is 80+/-5 mu m, the distance between the center point of the stress area and the fiber core is 9.5-11.5 mu m, and the diameter of the stress area is 9-12 mu m.
2. The 40 μm-diameter panda-type polarization maintaining fiber according to claim 1, wherein: the coating layer comprises an inner coating layer and an outer coating layer, wherein the inner coating layer and the outer coating layer are coated on the outer side of the coating layer, the inner coating layer and the outer coating layer are made of double-layer acrylic resin materials solidified by ultraviolet light, the elastic modulus of the inner coating layer is 0.05-10 mpa, and the elastic modulus of the outer coating layer is 500-3000 mpa.
3. The 40 μm-diameter panda-type polarization maintaining fiber according to claim 1, wherein: the stress region is a circular structure made of borosilicate glass, and the doping concentration of the stress region is that the refractive index difference of the stress region relative to the quartz glass is-0.012 to-0.018.
4. The 40 μm-diameter panda-type polarization maintaining fiber according to claim 1, wherein: the operating wavelengths are 1310nm and 1550nm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322299417.XU CN220543151U (en) | 2023-08-25 | 2023-08-25 | 40 micron small-diameter panda type polarization maintaining optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322299417.XU CN220543151U (en) | 2023-08-25 | 2023-08-25 | 40 micron small-diameter panda type polarization maintaining optical fiber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220543151U true CN220543151U (en) | 2024-02-27 |
Family
ID=89974238
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322299417.XU Active CN220543151U (en) | 2023-08-25 | 2023-08-25 | 40 micron small-diameter panda type polarization maintaining optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220543151U (en) |
-
2023
- 2023-08-25 CN CN202322299417.XU patent/CN220543151U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5482525A (en) | Method of producing elliptic core type polarization-maintaining optical fiber | |
| CN111290073A (en) | 60-micron small-diameter panda-type polarization maintaining optical fiber and preparation method thereof | |
| US4599098A (en) | Optical fiber and method of producing same | |
| US8635889B2 (en) | Refraction-sensitive optical fiber, quartz glass tube as a semi-finished product for the manufacture-thereof and method for the manufacture of the fiber | |
| EP0381473A2 (en) | Polarization-maintaining optical fiber | |
| CN102193142A (en) | Bending-resistant large core high numerical aperture multimode fiber | |
| CN105985015B (en) | A kind of ellipse core polarization maintaining optical fibre and its manufacturing method | |
| CN110346864B (en) | Multi-core few-mode optical fiber and manufacturing method thereof | |
| EP2938579B1 (en) | Method of manufacturing preforms for optical fibres having low water peak | |
| CN112305664A (en) | Multipurpose polarization maintaining optical fiber and preparation method thereof | |
| KR20090127300A (en) | Reduction of optical fiber cane/preform deformation during consolidation | |
| CN101825738A (en) | Panda type polarization maintaining optical fiber | |
| US20030140659A1 (en) | Method for producing an optical fibre and blank for an optical fibre | |
| CN102757179A (en) | Method for preparing large-size optical fiber preform | |
| CN102385103A (en) | Optical fiber, optical fiber preform and method of fabricating same | |
| CN104777552B (en) | A kind of double-cladding active optical fiber and its manufacture method | |
| CN105911639A (en) | Low-attenuation single-mode optical fiber | |
| CN103030269B (en) | Multimode optical fibers | |
| CN105866880B (en) | A kind of preparation method of polarization maintaining optical fibre | |
| CN106338793B (en) | Few-mode optical fiber | |
| CN209946443U (en) | 60-micron small-diameter panda-type polarization maintaining optical fiber | |
| CN105985014B (en) | A kind of diamond shape covering polarization maintaining optical fibre and its manufacturing method | |
| CN110954987A (en) | Elliptical core-bow-tie type single-polarization structure optical fiber and manufacturing method thereof | |
| CN220543151U (en) | 40 micron small-diameter panda type polarization maintaining optical fiber | |
| US9416045B2 (en) | Method of manufacturing preforms for optical fibres having low water peak |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |